The present invention generally relates to electronic equipment, and more particularly to a method of monitoring an apparatus operating in a high temperature environment, such as a gas turbine engine.
Aircraft gas turbine engines undergo testing during their development, as well as during production and subsequent servicing. Numerous engine performance parameters are typically monitored to assess the performance of an engine, including various temperatures, pressures, flow rates, forces, rotational speeds, etc. As nonlimiting examples, it is typically desirable to monitor engine inlet, compressor and exhaust gas temperatures, pressures within the fan, compressor and turbine sections, fuel and airflow rates, compressor and fan rotor speeds, blade tip clearances, mechanical stresses and part vibrations. Development and flight test aircraft engines may be required to have thousands of sensors to monitor the various parameters of interest.
Engine testing is typically conducted on a stationary test stand that is often located outdoors. A nonlimiting example of such a test stand 100 is schematically represented in FIG. 1. The stand 100 is represented as including a vertical support column 102 mounted to a foundation 104 in the ground, and a head (thrust) frame 106 mounted on the column 102 from which an aircraft engine 108 is mounted for testing. The head frame 106 includes an adapter 110 to which the engine 108 is attached with a pylon 112 that is appropriately configured for the particular engine 108.
During engine testing, the engine 108 and its immediate surroundings can reach very high temperatures. For example, temperatures may approach or exceed 260° C. surrounding the engine core beneath the engine cowling (nacelle) 114, as well as on the head frame 106 and its adapter 110. While sensors used to monitor the engine 108 have been developed to withstand these temperatures, the electronics used to process the sensor data have been limited to much lower temperatures. For example, typical commercial electronic components are often limited to about 85° C., and even military standard components are typically rated to not higher than 125° C. As such, each sensor typically requires a separate continuous wire or tube to carry its output signal to a remote data acquisition system, which is often located within an enclosed facility equipped with a controlled environment. The facility may be a considerable distance from the engine test stand, for example, 50 meters to in excess of 300 meters. Routing, managing and maintaining the numerous (potentially thousands) of data wires and tubes requires a considerable effort. Consequently, the ability to reduce the length and number of wires and tubes would be helpful and beneficial.